Tagging items with barcodes or symbols that facilitate optical character recognition has long been used to identify and track product inventories, baggage, paper checks, or other movable items susceptible to misplacement or loss. Unfortunately, such optically perceptible tags must remain visible for identification, and can be easily rendered unreadable by surface marks or other damage.
To improve tracking reliability, attempts have been made to use radiofrequency based electronic tags. Such tags typically have a semiconductor memory for data storage, processing logic, and a small antenna for broadcasting data, all embedded in rugged epoxy, thermoplastic, or other suitable plastic containers. Data storage capacity typically ranges from a few bits to many kilobits, with 64 bits being typical. Tags can include read only memory (ROM), electrically programmable or erasable (EPROM and EEPROM), or even flash memory. An electronic tag can be powered by a long lasting small battery, photovoltaic power, thermal convertor, inductive power converter that relies on externally applied electromagnetic energy, or any other suitable power supply.
Unfortunately, since such electronic tags broadcast information when powered, use of large numbers of electronic tags in close physical proximity is difficult. For example, if multiple electronic tags are situated within a few centimeters of each other, their overlapping data broadcasts could interfere with each other, making it difficult to determine tag identity. Such problems have generally limited electronic tag placement by requiring only one tag per object, with each object being well separated from each other during data transfer. This requirement has limited use of electronic tags in an office environment, where large numbers of tags could be profitably used for tracking papers, files, or other printed material.
In the modem office environment, the management of paper documents is not well coordinated with the management of their electronic counterparts. If an electronic tag is attached to a physical document, a user can access some associated virtual representation (e.g. an ASCII text file) by placing it near an augmented computer equipped with a tag reader. The resulting system is a powerful tool for maintaining a bridge between physical and virtual representations of documents, or, in general, for augmenting physical objects with virtual associations. Advantageously, the present system can be used to track multiple tagged documents in close proximity, or to allow performance of various selected services (e.g. printing, e-mailing, discarding electronic copies, opening electronic applications)
The present invention meets these requirements by providing a system for identifying multiple electronic tags that includes a plurality of electronic tags attachable to a single object, each electronic tag having a non-overlapping readable region, and each electronic tag having a unique identifier. One or more electronic tag readers are configured to read the unique identifier of each electronic tag within the non-overlapping readable region, and a computing system is connected to the electronic tag reader to provide digital services in response to reading the unique identifier of each electronic tag. In certain embodiments, the electronic tags can have integral sensor systems that detect, for example, light, location, acceleration, or other physical properties, allowing provision of particular digital services related to the sensed properties.
Such a system is particularly useful for multiple tagging of substantially three-dimensional objects (solids) or two-dimensional objects (sheets) with large numbers of distinct electronic tags. For example, a multifaced solid such as a polygon can have each face, edge, or vertex equipped with a unique electronic tag that invokes a digital service (or provides parameters for enabled digital services). Various symbolic indicia such as text, graphics (pictures or line drawings), color codings, texture codings, etc. can be used to assist a user in associating a particular tag with a digital service.
The foregoing electronic tags can be read by tag readers attached to desktop computers, or in certain embodiments, by tag readers integral or closely attached to portable or hand holdable computers. Such portable computers can also support wireless network transceivers for communication with a computer network, extending the range of supported digital services.
In operation, at least one electronic identification tag is affixed to each physical item that is associated with digital services. These tags can be small radio frequency transponders comprised of an integrated circuit, containing a unique user accessible 39-bit identification number. A small coil inductively powers the tag, and an antenna is used to broadcast the identification number. In certain embodiments, the antenna can be separate from the coil, or alternatively, a dual-use inductive power coil/antenna coil can be used.
A tag reader that includes transmitter and receiver components is affixed to a computational device such as a hand held computer. The tag reader transmits a pulse that momentarily energizes the tag through its coil until it has sufficient power for transient transmission of its identification number. The communication between tag and tag reader only occurs when both are proximate, with an actual distance varying based on size of the antenna attached to the tag and to the transmitter, from a distance of a few inches to that of several feet. Once the identification number (transmitted serially) is received, the tag reader passes this on to the computer system as an ASCII string, via a serial RS-232 output or some other suitable connection, while simultaneously providing user feedback to confirm reading of the tag. User feedback can be visual (e.g. blinking or turning on an LED status light, text based or iconic display presentations), auditory (e.g. an audible buzz or beep), tactile (e.g. a button being raised or a perceptible structure rotation), or combinations of the foregoing.
Upon receipt of the identification number, a computer based application program interprets the identification input string, determines the current application context, and provides appropriate digital services. For example, an ASCII database that maps identification numbers to one or more digital services can be used. One common action is a (program, identification number) pair that invokes the identified program on the associated identification number. If the received identification number has not been previously registered, i.e. associated with an action in the ASCII database, the user can be prompted to enter an action(s) and any associated parameters via a dialog box. Network and server connectivity is provided by a separate wireless radiofrequency or infrared networking system. If the program or the file to be retrieved reside on the network, filenames that are independent of the particular sensing computer can be used.
In addition to an identification number, certain embodiments of tags in accordance with the present invention can convey small amounts of modifiable data (maintained, e.g., in flash memory). For example, data provided by sensors embedded or attached to the tag can be used to detect folding, twisting, or bending of the tagged object. Alternatively, a number of accelerometers that sense relative spatial information; gyroscopic, radio or infrared positional sensors for determining absolute position; and various thermal or photosensors that respectively detect temperature and light level changes can provide sensed data values for later transmission by the tag. Intentional or unintentional modifications detected by one or more of these sensor systems, taken in conjunction with the particular tag presented to the tag reader, can provide the basis for a powerful user interface scheme.
As those skilled in the art will appreciate, each identification number or sensed data value that is read (sensed) by the tag can be labeled as a "senseme", with a particular digital service or attribute being associated with each senseme. Although the wide variety of easily distinguishable sensemes (e.g. identification numbers) would alone provide a powerful user interface to a computer, the present invention further extends the flexibility of the senseme based user interface by supporting computer control based on a multiple senseme input, with temporally synchronous (or overlapping asynchronous) tuples of one or more sensemes (e.g. particular identification numbers and sensed states) being read by the tag reader. Single and multiple sensemes can in turn be extended by participation in a "sentence". A sentence is defined as a sequence of one or more temporally disjoint sensemes or senseme tuples. The sentence level allows definition of a input grammar by appropriate choice of senseme sequence, and corollary rules governing, for example, use of active verb-like sensemes (e.g. "print"), naming noun-like sensemes (e.g. DOC1.TXT), or connectors (e.g. AND).
In effect, the present invention provides a method for transferring information from a tagged object with optional sensors to a tag reader connected computer. The method comprises the steps of manipulating one or more tags and optional tag sensors to provide a first senseme input (that includes the tag identification number) to the computer, with the first senseme input normally triggering a first default action by the computer. The tagged object may also be manipulated to provide a second senseme input (again including a tag identification number) to the computer, with the second senseme input converting the normally triggered first default action to a second action. The first and second sensemes (and any subsequent sensemes) together form a sentence that can be interpreted as a command to implement a computer controlled action, whether it be to open and print a particular electronic document, unlock an electronically controlled door in response to a tag conveyed personal identification number, display a graphical image on a computer display, or begin logging on to a computer network. In operation, for example, the sentence "establish authorization, open a file, and print the file to printer number 3" can involve the sequential steps of reading a first tag embedded in a picture identification card to establish user identification, immediately presenting a second tag clipped to a paper document to specify a related electronic document and finally presenting a three dimensional token that appears like a small printer with an embedded third tag and pressure sensor that initiates printing of the previously specified document at printer number 3 after pressure sensors electrically connected to the tag are squeezed three times. The foregoing operation conveniently distinguishes particular electronic documents, and allows a user to select particular printers, (e.g. with printer 1 requiring one sensed squeeze and printer 2 requiring two sensed squeezes) without requiring visual displays or complex input commands.
Utility of the foregoing system can be extended by selective shielding of the electronic tag. Shielding can be used to arbitrarily limit the readable range or provide strong directional reading properties for the electronic tag, a particularly useful feature when large numbers of electronic tags are positioned near each other. According to the present invention, an electronic tag including a processor, a readable memory for holding an identification number connected to the processor, an antenna connected to the processor for radiofrequency broadcasting of the identification number, and a power supply for powering the antenna to broadcast the identification number is provided with an electromagnetic shield positioned near the antenna for reducing broadcasting range of the antenna. The shield can, for example, be metallic wire or sheeting positioned at least partially around or near the antenna, or metal lined cavities into which the electronic tag is attached. Such shields in accordance with the present invention reduce reading range and can limit reading of the tag to specific directions. For example, electronic tags can be partially surrounded with shields to limit readable electromagnetic radiation to a direction substantially normal to the surface of an object to which the tag is attached. Such shields would allow large numbers of electronic tags to be closely spaced on an object, since interfering lateral electromagnetic radiation from adjacent tags would be inhibited.
In certain embodiments, the electromagnetic shield is movable between a first substantially non-blocking position and a second blocking position that respectively unblocks and blocks antenna broadcast. The movable electromagnetic shield can be biased to remain in its first substantially non-blocking position to allow antenna broadcast, or alternatively biased to remain in its second blocking position to block antenna broadcast. Advantageously, a user movable shield also permits use of the electronic tag as a user defined communication channel for transmitting small amounts of information. If an electronic tag having a transmitted identification number is controllably shielding and deshielding to provide a user defined time series of readable and non-readable intervals for the transmitted identification number, the consequent user defined time series of readable and non-readable intervals for the transmitted identification number can be interpreted as bit-wise communication associatable with the transmitted identification number. In effect, a user could send bit codes by intermittently interrupting reading of the electronic tag (or alternatively, by intermittently allowing reading of the electronic tag). Such small amounts of user defined and transmitted information can be used to parameterize digital services associated with the transmitted identification number, or can even be used as personal identification numbers or verifiers to initiate triggering of a digital service in response to reading an electronic tag. For example, a tag reader can be configured to launch an application only after receipt of two pulses (clicks) of a particular identification number. Such a mechanism reduces inadvertent or unwanted triggering of a digital service ordinarily provided in response to reading an electronic tag.
In addition to selective shielding, the present invention provides for selective enablement and disablement of electronic tags. This is yet another mechanism that eases problems associated with use of large numbers of closely placed electronic tags, and also allows for some limited user defined communication. An electronic tag having a processor, a readable memory for holding an identification number connected to the processor, an antenna connected to the processor for radiofrequency broadcasting of the identification number, a power supply for powering the antenna to broadcast the identification number, is also provided with an interconnect switch for interconnecting at least two members selected from a set defined by the processor, readable memory, antenna, and power supply. The interconnect switch can be biased to remain normally open, preventing broadcast of the identification number, or alternatively, can be biased to remain normally closed, allowing broadcast of the identification number.
As will be appreciated, the interconnect switch can be connected between the antenna and one of the processor and the power supply, with opening or closure being controlled by a user that opens or closes electrical contacts in the interconnect switch (using any conventional button, contact switch, electrical switch, or other conventional switch known to those skilled in the art). In certain embodiments, a sensor can be connected to the processor, and the interconnect switch is alternately opened and closed in response sensor data provided by the sensor. For example, an electronic tag can be equipped with an accelerometer capable of signaling when the tag is nudged or shaken. Normally, the tag remains disabled with its interconnect switch open. If the tag is moved, shaken, or nudged, the accelerometer senses the transient accelerations and sends a signal to the interconnect switch to close, allowing the electronic tag to broadcast its identification number. A second shaking reverses the foregoing, causing the sensor to signal the interconnect switch to open and break the antenna/power-supply connection (for example), disabling the electronic tag. Sensor systems responding to heat, light, sound, force, or any suitable effect can be employed in the present invention.
As noted previously in connection with movable shields, user defined enablement or disablement of the electronic tags can be used for low bit rate communications directed by a user. Controllably switching an interconnect switch of an electronic tag having a transmittable identification number provides a user defined time series of readable and non-readable intervals for the transmitted identification number. This user defined time series of readable and non-readable interval for the transmitted identification number can be readily interpreted as bit-wise communication associatable with the transmitted identification number.
Additional functions, objects, advantages, and features of the present invention will become apparent from consideration of the following description and drawings of preferred embodiments.